Field of the Invention
The invention relates to a method for producing a formed part furnished with a through hole and to a device for carrying out the method.
Description of Related Art
Such a method is known for example from DE 31 47 897 A1. According to that document, identical annular metal parts are produced without cutting from a metallic rod material by swaging and the resulting deformation of an end portion of the rod material to form a disc, followed by axial perforation of the disc with a punch having the same cross-sectional shape as the (uncompressed) rod material, and separation from the disc of the disc core that is perforated by the punch. The disc core and the uncompressed rod material portion together constitute an integral part and the starting point for a subsequent process cycle until there is no longer enough rod material remaining to form any more formed parts and the remainder is lost as waste.
When the disc core is perforated, the shear and tensile stresses generated give rise to an undesirable fracture surface with cracks and possibly buns on the peripheral edge of the hole in the disc formed thereby, possibly necessitating reworking of the formed parts.
An object of the invention is therefore to improve a method of the type described above in such manner that the formed parts produced thereby require substantially less reworking, if any. In addition, no burrs or other deformations that would hinder the subsequent processing steps should occur at the separation sites of the rod material.